Screening apparatus for separating material



Dec. 5, 1961 B. HOLMAN 3,011,639

SCREENING APPARATUS FOR SEPARATING MATERIAL Filed March 4, 1958 LEE 5. HJLMA/v,

INVENT OR.

BY y

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United States Patent Lee B. Holman, Whittier, Califi, assignor to State Steel Products, Inc., Puente, Califi, a corporation of California Filed Mar. 4, 1958, Ser. No. 719,470 9 Claims. (Cl. 209-274) This invention relates to an apparatus and method for separating material of diilerent particle size and of different characteristics and more particularly relates to a composite screen means for use with such a separating apparatus.

This invention particularly relates to separators of gyratory type employed for separating material of selected particle size in either wet or dry processes. Prior proposed gyratory separators have included a rigid, hollow frame means across which a screen fabric of selected mesh was stretched. In such prior proposed devices the screen fabric was usually positioned in a horizontal or slightly inclined planar zone. In some instances means were provided at the center of the screen for positioning the center of the screen either above or below the normal planar zone of the screen fabric so as to assist in imparting either radially inward or outward motion components to material being separated on the screen fabric. When material was introduced adjacent the center of such a screen fabric, gyratory motion of the screen fabric imparted an enlarging spiral fiow path to particles being separated. Because of flexibility of the screen fabric and the difficulty of obtaining uniform tension in the screen fabric, there were often dead areas of no particle movement or excessive accumulation of material in the flow pattern of the particles on the screen fabric and eflicient separation of particles was not accomplished. In such prior proposed devices material being separated often tended to accumulate about the circumference of the screen fabric and against the side wall of the screen frame means.

in l the present invention a novel composite screen constructionvis employed to produce a highly eficient separation of particles in a gyratory separatordevice and contemplates a screen means presenting enlarged efi'ecti ve screen area in a predetermined space normally containing less screen area for greatly increasingthe capacity of a gyratory separator or selected size.

Generally speaking, the composite screen construction of this invention comprises a hollow screen frame means of usual rigid structure and a composite screen means which includes an outer annular screen portion connected to the frame means at its outer circumferential edge and connectedat its inner circumferential edge to the base of an inner centrally located cone-shaped screen portion which rises above the annular, portion. The vertex of the cone is supported by an upstanding bolt disposed coaxial with the annular portion so that thev cone-shaped inner screen portion presents, to a fiowable mass of mate.- rial being fed at its vertex radially outwardly. and downwardly disposed screen surfaces for rapidly dispersing and thinm'ng the flowable, mass of material, being separated in a relatively short distance of travel. As a result of this construction, material to be separated is provided with a rapid initial separation of certain particles, the material is uniformly dispersed to the annular portion in a relatively thin fiowable mass, and the motion of the material on the outer portion at the. base of the coneshaped inner portion produces an agitated temporary mass of accumulated material wherein certain, such as, finer particles of material move beneath the agitated mass for rapid separation therefrom.

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The primary object of this invention, therefore, is to disclose and provide a novel, eiiicient separator apparatus of high capacity.

An object of this invention is to disclose and provide a composite screen means for use in a separating apparatus for simultaneously imparting to material being separated along angularly related screen surfaces motion components which produce efiective, rapid separation of the material.

Another object of this invention is to disclose and provide a novel method of separating material wherein a relatively confined material mass is rapidly, laterally dispersed in the direction of its feed path so as to form a thinned fiowable material mass, the mass of material being subjected to oscillatory agitation as it is being laterally dispersed in a downward direction.

Another object of this invention is to disclose and rovide a composite screen means for a separator apparatus wherein the screen means comprises an inner screen portion and an angularly related outer screen portion, said inner screen portion being encircled by said outer screen portion.

A still further object of this invention is to disclose and provide a composite screen means wherein a virtually continuous screen fabric i arranged in such a manner that more than two material separations may be accomplished.

A further object of this invention is to disclose and provide a composite screen construction including a coneshaped inner screen portion and an annular outer screen portion assembled in such a manner that said screen construction maintains preselected tension when used in the separation of hot material.

A still further object or" this invention is to disclose and provide a composite screen construction as mentioned above wherein the openings in the mesh of the screen fabric of the inner and outer portions may be, of similar or difierent area or size.

Various other objects and advantages of this invention will be readily apparent from the following description of the drawings in which an exemplary embodiment of the invention is shown. i

In the drawings:

FIG. 1 is a vertical sectional view of a separator apparatus provided with a composite screen means of this invention.

FIG. 2 is a fragmentary top view of the screen means shown in FIG. 1. V 1

FIG. 3 is a fragmentary perspective view of the con;- posite screen means showing generally the. flowv paths of material being separated l 7 FIG. 4 is a fragmentary sectional View showing a detachable mounting for the cone-shaped screen portion.

The separator apparatus generally indicated at 10 may comprise a construction as shown in co-pending application Serial No. 592,176 filed June 18, 19 56, inventors, Lee B. Holman, and William T. Smith, now Patent 2,950,819. The separator apparatus may be of gyratory type and may include. a base frame 11 fixed to a supporting surface and circular receptacle means generally indicated at 14 resiliently supported from said base frame ll byfmeans of circumferentially spaced coil springs 15. Ihe receptacle means 14v for receiving material to be separated may include one or a plurality of. separation stages in staclced relation. In this, example, only one separation stage is illustrated which provides two separations or classifications of material.

Means for oscillating or agitating in gyratingimanner the receptacle means 14.: may comprisea motor means 16 carried by the base frame 11- and adapted to drive a drive shaft 17 through a drive pulley means 18. The drive shaft 17 may be anti-frictionally mounted by well known means in a bearing housing 19 carried by the base frame 11, said drive shaft 17 having a connection with the receptacle means 14 through a cylindrical depending housing 20 enclosing a self-aligning hearing as described in the said co-pending application. Eccentric mounting means are provided so that the receptacle means 14 may be oscillated in such a manner as to provide a progressively tilting gyratory motion to the receptacle means 14 to facilitate separation of material. Material to be separated may be fed to the receptacle means 14 by a suitable downwardly directed chute or duct 21 centrally positioned over the receptacle means.

The receptacle means 14 may comprise a pair of outwardly facing channel section annular rigid hollow frame members 23 and 24 of like inner diameters, member 24 being seated on top of member 23. A dome shaped imperforate bottom wall 25 may be secured as by welding to the member 23 and material falling thereon may be discharged from bottom wall 25 through a duct 26 provided at the peripheral side wall of the member 23. The frame member 24 may be seated on the member 23 and secured thereto in well known manner as by a plurality of nut and bolt assemblies 27. A discharge duct 28 may be provided at the side wall of member 24 for discharge of material therefrom. It will be understood that one or more of frame members 24 may be stacked upon the member 23 depending upon the number of successive screening or separation operations desired.

A composite screen means generally indicated at 30 extends across the interior of the receptacle means. The composite screen means 30 may include an outer annular band or circumferential screen portion 31 of se lected uniform'width and of selected screen fabric, said outer annular screen portion 31 having its outer circumferential edge margin 32 secured between top and bottom annular surfaces respectively of frame members 23 and 24 in any suitable well known manner. Inner circumferential edge 33 of outer screen portion 31 may be secured to a contigous circumferential edge 34 of the base of a cone-shaped uprising inner screen portion 35. Adjacent edges 33 and 34 of portions 31, 35 respectively, may be bonded or secured together in any convenient manner. One exemplary method for bonding said edges 33, 34 together may be welding by means of liquid metal.

The cone-shaped inner screen portion may be fabricated in any suitable manner as by cutting virtually triangular or sector shaped screen sections and then joining the sections along their side edges to form a cone shape. If desired, the cone-shaped screen portion may be made of one piece by unfolding or laying out the cone pattern in a plane so that a flat screen fabric may be cut and then formed into a cone shape, the seam being secured together as by welding or liquid metal.

The cone-shaped screen portion 35 may be self-supporting and readily detachable from the outer portion 31. For this purpose, the base of portion 35 may be provided with an annular ring 50 which may be superimposed over a mating annular ring 51 secured to the inner circumferential edge of the outer screen portion 31. The mating rings may be secured together as by screw bolts, however, since the downard pressure of material being separated presses the inner screen portion on the outer screen portion, alignment and non-relative movement therebetween may be provided by openings 52 in the ring on the outer screen portion and cooperable depending pins 53 on the ring on the inner screen portion. Thus a detachable cone may be readily replaced to change screen size or to substitute a new cone-shaped screen for a worn screen.

The inner screen portion 35 terminates at a vertex 36 lying above the plane of the outer screen portion 31 and at said vertex the cone-shaped inner screen portion 35 may be attached to the top end of floating downwardly biased coaxial bolt 37 by a nut and washer assembly 38. A tension spring 39 below the screen fabric may interconnect the lower end of the bolt 37 with a transverse member 23a carried by the hollow frame member 23. In this example, the inclination of the cone-shaped'surfaces may be disposed at an angle of approximately 30 degrees with respect to the plane of the outer annular screen portion 31. It will be understood that for different types of material to be separated it may be desirable to vary the angle of the cone to provide the most efiicient separation.

It will be understood that the size of openings in the outer screen portion 31 and the inner screen portion 35 may be identical; that is, of the same mesh, or the openings may be of different size, the outer portion 31 having either a larger or smaller mesh size than inner screen portion 35. In the example shown in FIG. 1, it is contemplated that the mesh of the inner screen portion 35 is relatively fine and for this purpose a reinforcing wire network is provided in order to reinforce the relatively fine mesh of the screen portion 35 to hold the inner screen portion in selected configuration. Such a reinforcing network may comprise a plurality of concentrically arranged wire elements 40 of progressively diminishing diameter and arranged in spaced relation. Holding the concentric wire elements 40 in selected spaced relation may be a plurality of angularly spaced radially downwardly extending wire elements 41. The elements 41 may terminate in a base ring 42 provided at the intersection of the edges 33 and 34 and in this example base ring 42 may provide metal to which the screen edges 33, 34 may be secured as by welding. It will be understood that when the inner screen portion 35 is formed of relatively large mesh having wire elements of substantial strength, the reinforcing wire network including elements 40, 41 and 42 may not be required or used.

In the fabrication of the composite screen means 30, it may be desirable to prestretch or pretension the inner cone-shaped screen portion 35 by means of wire elements 41 so that when the inner portion 35 is attached to the bolt 37 and the annular outer screen portion 31 is tensioned in the screen frame means the conical walls of the inner screen portion 35 will be under tension and will not sag. Adjustable tensioning of the outer screen portion 31 will position the screen fabric of portion 31 in a generally horizontal zone as indicated. It will be understood, of course, that the relationship between the vertex and base of the cone-shaped portion'and circumferential outer edge 32 of the outer screen portion 31 may be of such varied dimension so that the outer screen portion 31 may be inclined either downwardly or upwardly with respect to the horizontal plane defined by the frame of the receptacle means 14. The included angle between the cone surfaces and the outer annular portion may thus be varied.

It should be also noted that with the inner screen portion 35 having surfaces lying in angular relation to the generally horizontal outer screen portion 31, the flow of material is downwardly across the inclined surfaces of screen portion 35 and in such downward flow the openings of the mesh of the inner screen portion 35 may be somewhat larger than the outer screen portion in order to present to vertical movementof the particles being separated openings of a size similar to those in the outer screen portion when viewed from directly above the inner portion 35. This relationship will be discussed hereinafter in a description of the operation and method of separating material with the composite screen means described above.

The above described separating apparatus and composite screen means may be used for the separation of either a dry flowable mass of material or a wet mass of material employing liquid as a conveying fluid or vehicle. Operation of the apparatus will be described in relation to separation of a dry flowable material mass. Such material may contain particles of different size and characteristic and may be fed through the feed duct 21 by gravity in a relatively compact or confined flowable mass which moves along a path generally defined by the axis of the duct 21. The axis of the duct 21 may be aligned with or be disposed at a slight angle to the axis of the composite screen means and may be spaced above the vertex of the cone a suitable selected distance. As the fiowable mass is poured onto the vertex of the inner cone-shaped screen portion, the cone-shaped screen causes the flowable mass to expand laterally or radially outwardly from the axis of the cone and to disperse very rapidly the relatively confined compact flowable mass of material. As the flowable mass is dispersed on the inclined surfaces of the coneshaped screen the fine particles readily sift through the larger particles and pass through the openings in screen portion 35 to cause immediate separation of the fines or very small particles in the mass. Because of the rapid thinning out of the flowable mass on the inclined surfaces the greatest portion of the smaller particles passable through the screen portion 35 are separated at the inner screen portion.

As the thinned flowable mass travels upon the inner margins of the outer annular screen portion, the gyratory motion imparted to the composite screen means temporarily produces an active agitated accumulated mass of material at the base of the cone. It has been found that when gyratory motion is in a counterclockwise direction, for example, agitation of the smaller particles and remaining fines appear to be in clockwise direction as viewed from the side ofthe composite screen means. In such clockwise motion the fines tend to slide under the turbulent boiling mass of material at the base of the cone and are rapidly separated on contiguous portions of the outer screen portions.

As the material at the base of the cone is subjected to further agitation by the gyratory separator the heavier particles and the larger particles tend to move in curvilinear paths toward the other circumferential margin of the outer annular screen portion. It will be readily apparent that the material leaving the base of the cone is relatively uniformly distributed in directions away from the axis of the screen means by the agitation of the apparatus. As the particles travel along the wall surface of the frame means, they are led to the discharge duct and only those particles too large to pass through the mesh of the screen portions are discharged.

The movement and separation of the particles as above described may be further explained by noting that the eccentric means provided along the axis of the receptacle means 14 in association with drive shaft 17 imparts motion to the receptacle means which includes horizontal, vertical and gyratory motion components. It will be apparent that the location of the eccentric means and the resilient coil springs at the periphery of the receptacle means provides a relatively small vertical motion component imparted to particles at the cone screen while a relatively larger vertical motion component is imparted to the particles at the annular screen portion. Thus provision of the cone shaped screen at such central area or location of relatively small vertical motion components imparted to the screen by the motion imparting means not only tends to immediately laterally distribute the particles fed to it but also effectively utilizes the vertical motion component in the falling particle itself as it is fed in order to produce initial separation of the fines or smaller particles. The provision of the annular screen portion at an area where vertical motion components are larger elfectively utilizes the larger vertical motion components produced adjacent the periphery of the composite screen.

The distribution pattern of particles separated by the composite screen means virtually eliminates the inclusion of undersized particles at the discharge duct because fines are separated at the cone-shaped screen portion, coarse fines adjacent the base of the cone, and by the time the particles reach the outer edge of the annular screen portion 31,'they are virtually not less than screen size. Since the undersized particles are so rapidly eliminated, the composite screen may handle more material. It has been found that the greater the rate of feed of material, the faster the separation since the cone screen portion assists in the speed of travel of the particles and the pressure of moving particles against particles on the cone screen eliminates blinding of the screen mesh and has a self-cleaning effect on the screen.

While the above operation has been described with respect to a composite screen means having an inner screen portion of mesh smaller than the outer screen portion, it will be understood that when the inner screen portion is provided with selected larger openings in inclined relation that such larger openings may present to downwardly moving particles an effective opening which is the same size as the mesh openings of the outer screen portion. In other Words, the projection of the inclined opening to a plane parallel to the outer screen portion will provide a projected area of the inclined opening approximately equivalent to the area of an opening in the outer screen portion. The provision of inner and outer screen portions having mesh openings so related provides a screen means of enlarged efifective screen area for rapid separation of material.

When the composite screen means of this invention is used to separate material which is made flowable by a liquid such as water, it will be readily apparent that the separating'operation is'subs'tantially the same as that above described. The cone-shaped inner portion provides a means for immediately separating the liquid from the ma terial conveyed thereby with the result that immediate separation of particles of material may commence.

It will be readily understood that depending upon the type of material to be separated various modifications may be made in the relative sizes of mesh employed in the inner and outer screen portions, in the selected angle for the inclined screen surfaces of the cone, and in the amount of screen area apportioned to the inner and outer screen portions. It will also be readily apparent that for certain types of material it may be desirable to modify the shape of the inner screen portion to one which is not cone-shaped. For example, the inner screen portion may be ellipsoidal, semi-spherical or any other suitable curvilinear or linear configuration.

Since the inner screen portion rapidly, effectively separates particles of selected size and dependent upon the degree of separation required, the particles passed through the inner screen portion may be separately collected and discharged, particles passed through the outer screen portion collected and discharged through duct 26 and all particles not passed by the screen means discharged through duct 28. A suitable partition wall (not shown) may be carried by the bottom Wall beneath the base of the cone-shaped inner portion to form a collection area for particles beneath the cone and a discharge opening may be provided in the bottom wall, if desired.

It is important to note that the shape of the inner screen portion provides a means for self-adjustably maintaining the outer screen portion under tension when a hot flowable mass is being separated. It should be noted that the inner and outer edges of the outer annular screen portion are concentric and are relatively, rigidly held, the inner circumferential edge being provided substantial rigidity because of the welding therealong to the base portion and thereby provided with substantial metal as compared to adjacent screen portions. As mentioned above, the inner screen portion is prestretched and the tension of the screen means is adjusted in the outer screen portion. Thus, when hot material is dispersed by the coneshaped inner portion, expansion of the inner screen portion occurs which produces a downward displacement of metal at the base of the cone and such downwardly di- 7 rected expansion forces tend to maintain the outer screen portion under tension.

It Will be readily understood by those skilled in the art that modifications and changes of the composite screen means may be made in separator apparatus of different construction which embody the spirit of this invention, and all such modifications and changes coming within the scope of the appended claims are embraced thereby.

I claim: I

1. In a gyratory separator apparatus for rapidly separating particles of material of different size from a flowable mass of such particles, the combination of: a frame means; a receptacle means resiliently supported on the frame means and having a vertical axis; means along said axis to impart horizontal, vertical, and gyratory motion to the receptacle means; and means for feeding particles of material to be separated to said receptacle means along a feed path substantially vertical and at said axis; said receptacle means including means adjacent said axis to initially separate particles of smaller size from said flowable mass of particles While said particles are imparted only small vertical motion components by said gyratory motion imparting means, and means remote from said axis for then separating particles of larger size from the remaining unseparated mass of particles While said larger size particles are imparted larger vertical motion components and substantial horizontal motion components by said gyratory motion imparting means.

2. A gyratory separator as stated in claim 1 wherein said means adjacent said axis to initially separate particles of small size includes a cone-shaped screen member having its vertex proximate to said feeding means.

3. A separator as stated in claim 2 including means on said cone-shaped screen member for maintaining said screen mesh under tension and whereby said screen member is self-supporting.

4. A separator apparatus as stated in claim 1 wherein said means for initially separating particles of smaller size includes a screen member downwardly inclined and extending from adjacent said axis.

5. A separator apparatus as stated in claim 1 wherein said means adjacent said axis and said means remote from said axis include screen members of difierent geometrical shapes and whereby the total aggregate screen area of said screen members exceeds the area defined by the periphery of the receptacle means.

6. A separator apparatus as stated in claim 2 including means connecting said frame means with the vertex of said cone-shaped screen member for biasing said coneshaped screen member.

7. A separator apparatus as stated in claim 1 wherein said means adjacent said axis and said means remote from said axis include respectively a cone-shaped screen member and an annular screen member, and rigid'ring means connecting the base of the cone-shaped screen member and the inner periphery of the annular screen member.

8. An apparatus as stated in claim 7 wherein said rigid ring means includes detachable means for readily separating the cone-shaped screen member from the annular screen member.

9. An apparatus as stated in claim 1 wherein said means adjacent said axis and said means remote from said axis include screen members of different geometrical shapes and wherein the said screen members are provided with openings of different size.

References Cited in the file of this patent UNITED STATES PATENTS 82,011 Lindsley Sept. 8, 1868 456,584 Morse July 28, 1891 545,185 Yost Aug. 27, 1895 1,284,095 Gruender Nov. 5, 1918 1,459,840 Mitchell June 26, 1923 2,696,302 Miller Dec. 7, 1954 FOREIGN PATENTS 113,165 Switzerland -n. Dec. 16, 1925 

